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Viewing changes to contrib/NGit/NGit.Revwalk/PendingGenerator.cs

  • Committer: Bazaar Package Importer
  • Author(s): Jo Shields
  • Date: 2011-06-27 17:03:13 UTC
  • mto: (1.8.1 upstream)
  • mto: This revision was merged to the branch mainline in revision 54.
  • Revision ID: james.westby@ubuntu.com-20110627170313-6cvz3s19x6e9hqe9
Import upstream version 2.5.92+dfsg

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contrib/NGit/NGit.Revwalk/PendingGenerator.cs
 
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/*
 
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This code is derived from jgit (http://eclipse.org/jgit).
 
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Copyright owners are documented in jgit's IP log.
 
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This program and the accompanying materials are made available
 
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under the terms of the Eclipse Distribution License v1.0 which
 
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accompanies this distribution, is reproduced below, and is
 
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available at http://www.eclipse.org/org/documents/edl-v10.php
 
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All rights reserved.
 
11
 
 
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Redistribution and use in source and binary forms, with or
 
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without modification, are permitted provided that the following
 
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conditions are met:
 
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- Redistributions of source code must retain the above copyright
 
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  notice, this list of conditions and the following disclaimer.
 
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- Redistributions in binary form must reproduce the above
 
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  copyright notice, this list of conditions and the following
 
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  disclaimer in the documentation and/or other materials provided
 
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  with the distribution.
 
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- Neither the name of the Eclipse Foundation, Inc. nor the
 
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  names of its contributors may be used to endorse or promote
 
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  products derived from this software without specific prior
 
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  written permission.
 
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
 
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CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
 
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INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 
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OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 
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ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 
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CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 
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SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 
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NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 
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LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
 
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CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 
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STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 
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ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
 
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ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
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*/
 
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using NGit;
 
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using NGit.Errors;
 
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using NGit.Revwalk;
 
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using NGit.Revwalk.Filter;
 
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using Sharpen;
 
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namespace NGit.Revwalk
 
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{
 
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        /// <summary>Default (and first pass) RevCommit Generator implementation for RevWalk.
 
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        ///     </summary>
 
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        /// <remarks>
 
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        /// Default (and first pass) RevCommit Generator implementation for RevWalk.
 
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        /// <p>
 
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        /// This generator starts from a set of one or more commits and process them in
 
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        /// descending (newest to oldest) commit time order. Commits automatically cause
 
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        /// their parents to be enqueued for further processing, allowing the entire
 
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        /// commit graph to be walked. A
 
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        /// <see cref="NGit.Revwalk.Filter.RevFilter">NGit.Revwalk.Filter.RevFilter</see>
 
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        /// may be used to select a subset
 
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        /// of the commits and return them to the caller.
 
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        /// </remarks>
 
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        internal class PendingGenerator : Generator
 
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        {
 
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                private const int PARSED = RevWalk.PARSED;
 
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                private const int SEEN = RevWalk.SEEN;
 
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                private const int UNINTERESTING = RevWalk.UNINTERESTING;
 
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                /// <summary>Number of additional commits to scan after we think we are done.</summary>
 
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                /// <remarks>
 
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                /// Number of additional commits to scan after we think we are done.
 
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                /// <p>
 
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                /// This small buffer of commits is scanned to ensure we didn't miss anything
 
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                /// as a result of clock skew when the commits were made. We need to set our
 
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                /// constant to 1 additional commit due to the use of a pre-increment
 
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                /// operator when accessing the value.
 
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                /// </remarks>
 
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                internal const int OVER_SCAN = 5 + 1;
 
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                /// <summary>
 
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                /// A commit near the end of time, to initialize
 
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                /// <see cref="last">last</see>
 
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                /// with.
 
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                /// </summary>
 
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                private static readonly RevCommit INIT_LAST;
 
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                static PendingGenerator()
 
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                {
 
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                        INIT_LAST = new RevCommit(ObjectId.ZeroId);
 
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                        INIT_LAST.commitTime = int.MaxValue;
 
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                }
 
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                private readonly RevWalk walker;
 
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                private readonly DateRevQueue pending;
 
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                private readonly RevFilter filter;
 
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                private readonly int output;
 
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                /// <summary>
 
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                /// Last commit produced to the caller from
 
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                /// <see cref="Next()">Next()</see>
 
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                /// .
 
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                /// </summary>
 
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                private RevCommit last = INIT_LAST;
 
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                /// <summary>Number of commits we have remaining in our over-scan allotment.</summary>
 
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                /// <remarks>
 
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                /// Number of commits we have remaining in our over-scan allotment.
 
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                /// <p>
 
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                /// Only relevant if there are
 
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                /// <see cref="UNINTERESTING">UNINTERESTING</see>
 
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                /// commits in the
 
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                /// <see cref="pending">pending</see>
 
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                /// queue.
 
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                /// </remarks>
 
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                private int overScan = OVER_SCAN;
 
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                internal bool canDispose;
 
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                internal PendingGenerator(RevWalk w, DateRevQueue p, RevFilter f, int @out)
 
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                {
 
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                        walker = w;
 
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                        pending = p;
 
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                        filter = f;
 
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                        output = @out;
 
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                        canDispose = true;
 
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                }
 
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                internal override int OutputType()
 
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                {
 
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                        return output | SORT_COMMIT_TIME_DESC;
 
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                }
 
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                /// <exception cref="NGit.Errors.MissingObjectException"></exception>
 
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                /// <exception cref="NGit.Errors.IncorrectObjectTypeException"></exception>
 
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                /// <exception cref="System.IO.IOException"></exception>
 
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                internal override RevCommit Next()
 
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                {
 
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                        try
 
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                        {
 
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                                for (; ; )
 
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                                {
 
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                                        RevCommit c = pending.Next();
 
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                                        if (c == null)
 
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                                        {
 
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                                                walker.reader.WalkAdviceEnd();
 
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                                                return null;
 
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                                        }
 
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                                        bool produce;
 
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                                        if ((c.flags & UNINTERESTING) != 0)
 
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                                        {
 
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                                                produce = false;
 
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                                        }
 
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                                        else
 
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                                        {
 
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                                                if (filter.RequiresCommitBody())
 
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                                                {
 
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                                                        c.ParseBody(walker);
 
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                                                }
 
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                                                produce = filter.Include(walker, c);
 
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                                        }
 
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                                        foreach (RevCommit p in c.parents)
 
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                                        {
 
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                                                if ((p.flags & SEEN) != 0)
 
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                                                {
 
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                                                        continue;
 
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                                                }
 
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                                                if ((p.flags & PARSED) == 0)
 
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                                                {
 
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                                                        p.ParseHeaders(walker);
 
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                                                }
 
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                                                p.flags |= SEEN;
 
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                                                pending.Add(p);
 
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                                        }
 
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                                        walker.CarryFlagsImpl(c);
 
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                                        if ((c.flags & UNINTERESTING) != 0)
 
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                                        {
 
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                                                if (pending.EverbodyHasFlag(UNINTERESTING))
 
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                                                {
 
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                                                        RevCommit n = pending.Peek();
 
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                                                        if (n != null && n.commitTime >= last.commitTime)
 
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                                                        {
 
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                                                                // This is too close to call. The next commit we
 
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                                                                // would pop is dated after the last one produced.
 
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                                                                // We have to keep going to ensure that we carry
 
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                                                                // flags as much as necessary.
 
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                                                                //
 
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                                                                overScan = OVER_SCAN;
 
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                                                        }
 
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                                                        else
 
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                                                        {
 
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                                                                if (--overScan == 0)
 
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                                                                {
 
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                                                                        throw StopWalkException.INSTANCE;
 
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                                                                }
 
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                                                        }
 
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                                                }
 
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                                                else
 
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                                                {
 
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                                                        overScan = OVER_SCAN;
 
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                                                }
 
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                                                if (canDispose)
 
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                                                {
 
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                                                        c.DisposeBody();
 
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                                                }
 
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                                                continue;
 
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                                        }
 
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                                        if (produce)
 
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                                        {
 
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                                                return last = c;
 
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                                        }
 
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                                        else
 
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                                        {
 
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                                                if (canDispose)
 
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                                                {
 
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                                                        c.DisposeBody();
 
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                                                }
 
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                                        }
 
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                                }
 
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                        }
 
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                        catch (StopWalkException)
 
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                        {
 
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                                walker.reader.WalkAdviceEnd();
 
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                                pending.Clear();
 
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                                return null;
 
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                        }
 
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                }
 
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        }
 
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}